/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.handler.ssl.util;

import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.internal.PlatformDependent;

import javax.net.ssl.ManagerFactoryParameters;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.TrustManagerFactorySpi;
import javax.net.ssl.X509ExtendedTrustManager;
import javax.net.ssl.X509TrustManager;
import java.security.InvalidAlgorithmParameterException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.Provider;

/**
 * Helps to implement a custom {@link TrustManagerFactory}.
 */
public abstract class SimpleTrustManagerFactory extends TrustManagerFactory
{

    private static final Provider PROVIDER = new Provider("", 0.0, "")
    {
        private static final long serialVersionUID = -2680540247105807895L;
    };

    /**
     * {@link SimpleTrustManagerFactorySpi} must have a reference to
     * {@link SimpleTrustManagerFactory} to delegate its callbacks back to
     * {@link SimpleTrustManagerFactory}. However, it is impossible to do so,
     * because {@link TrustManagerFactory} requires
     * {@link TrustManagerFactorySpi} at construction time and does not provide
     * a way to access it later.
     *
     * To work around this issue, we use an ugly hack which uses a
     * {@link ThreadLocal}.
     */
    private static final FastThreadLocal<SimpleTrustManagerFactorySpi> CURRENT_SPI = new FastThreadLocal<SimpleTrustManagerFactorySpi>()
    {
        @Override
        protected SimpleTrustManagerFactorySpi initialValue()
        {
            return new SimpleTrustManagerFactorySpi();
        }
    };

    /**
     * Creates a new instance.
     */
    protected SimpleTrustManagerFactory()
    {
        this("");
    }

    /**
     * Creates a new instance.
     *
     * @param name the name of this {@link TrustManagerFactory}
     */
    protected SimpleTrustManagerFactory(String name)
    {
        super(CURRENT_SPI.get(), PROVIDER, name);
        CURRENT_SPI.get().init(this);
        CURRENT_SPI.remove();

        if (name == null)
        {
            throw new NullPointerException("name");
        }
    }

    /**
     * Initializes this factory with a source of certificate authorities and
     * related trust material.
     *
     * @see TrustManagerFactorySpi#engineInit(KeyStore)
     */
    protected abstract void engineInit(KeyStore keyStore) throws Exception;

    /**
     * Initializes this factory with a source of provider-specific key material.
     *
     * @see TrustManagerFactorySpi#engineInit(ManagerFactoryParameters)
     */
    protected abstract void engineInit(
            ManagerFactoryParameters managerFactoryParameters) throws Exception;

    /**
     * Returns one trust manager for each type of trust material.
     *
     * @see TrustManagerFactorySpi#engineGetTrustManagers()
     */
    protected abstract TrustManager[] engineGetTrustManagers();

    static final class SimpleTrustManagerFactorySpi
            extends TrustManagerFactorySpi
    {

        private SimpleTrustManagerFactory parent;

        private volatile TrustManager[] trustManagers;

        void init(SimpleTrustManagerFactory parent)
        {
            this.parent = parent;
        }

        @Override
        protected void engineInit(KeyStore keyStore) throws KeyStoreException
        {
            try
            {
                parent.engineInit(keyStore);
            }
            catch (KeyStoreException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new KeyStoreException(e);
            }
        }

        @Override
        protected void engineInit(
                ManagerFactoryParameters managerFactoryParameters)
                throws InvalidAlgorithmParameterException
        {
            try
            {
                parent.engineInit(managerFactoryParameters);
            }
            catch (InvalidAlgorithmParameterException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new InvalidAlgorithmParameterException(e);
            }
        }

        @Override
        protected TrustManager[] engineGetTrustManagers()
        {
            TrustManager[] trustManagers = this.trustManagers;
            if (trustManagers == null)
            {
                trustManagers = parent.engineGetTrustManagers();
                if (PlatformDependent.javaVersion() >= 7)
                {
                    for (int i = 0; i < trustManagers.length; i++)
                    {
                        final TrustManager tm = trustManagers[i];
                        if (tm instanceof X509TrustManager
                                && !(tm instanceof X509ExtendedTrustManager))
                        {
                            trustManagers[i] = new X509TrustManagerWrapper(
                                    (X509TrustManager) tm);
                        }
                    }
                }
                this.trustManagers = trustManagers;
            }
            return trustManagers.clone();
        }
    }
}
